Mine roof cable bolt and method

ABSTRACT

A mine roof bolt for use with resin including a strand cable. The bolt includes a head mechanism attached to the strand cable which preferably allows the strand cable to be turned in a first direction for mixing the resin and in a second direction opposite the first direction for tensioning the strand cable in the mine roof; although mixing and tightening can occur in the same direction. A method for placing a mine roof bolt in a mine roof.

FIELD OF THE INVENTION

The present invention is related to a mine roof bolt. More specifically, the present invention is related to a mine roof bolt for use with resin that comprises a multi strand cable that is preferably spun in a first direction for mixing the resin and in a second direction opposite the first direction to tension the cable, although spinning in the same direction for mixing and tensioning can also be used.

BACKGROUND OF THE INVENTION

In regard to the prior art using rigid tension rebar bolts, the method to mix the resin was by turning in one direction to mix, then the opposite direction to tension the system. The prior art teaches several stop mechanisms which are different.

U.S. Pat. No. 5,378,087—This patent has to do with straight insertion using a static mixer on top. No spinning or turning to mix resin.

U.S. Pat. No. 6,039,509—This patent teaches a method for mixing by turning the cable, however, it doesn't say turning one way first to mix resin, then the opposite way to tension.

U.S. Pat. Nos. 5,375,946 and 5,647,694—These patents mix and tension in one direction simultaneously. They are different in that they both use an expansion shell at the top of bolt.

Previous Methods to Mix Resin Using Stiff Rebar Inclused:

-   -   1. Delay nuts—such as a dome nut, shear-pin nut, and a tab-nut         which prevents the thread from moving through the nut during         mixing, all of these had mixing and tensioning occurring with         movement of the tensioning device in one direction.     -   2. McDowell System—uses mixing in one direction and then         tensioning in the other direction. The means to prevent movement         of the nut off the thread is by damaging the thread at the end         of the bolt.     -   3. Jim Earl System—uses a one-half nut welded at the end of the         threads of a rebar as a stop means during mixing backwards,         similar to McDowell.

BRIEF SUMMARY OF THE INVENTION

The present invention pertains to a mine roof bolt for use with resin. The bolt comprises a strand cable. The bolt comprises a head mechanism attached to the strand cable which allows the strand cable to be turned in a first direction for mixing the resin and in a second direction opposite the first direction for tensioning the strand cable in the mine roof.

The present invention pertains to a mine roof bolt for use with resin. The bolt comprises a strand cable. The bolt comprises means for allowing the strand cable to be turned in a first direction for mixing the resin and in a second direction opposite the first direction for tensioning the strand cable in the mine roof.

The present invention pertains to a method for placing a mine roof bolt in a mine roof. The method comprises the steps of placing a resin cartridge in a bore hole in the mine roof. There is the step of inserting the strand cable of the bolt into the borehole so it pierces the cartridge. There is the step of rotating a head mechanism of the bolt attached to the strand cable in a first direction to rotate the strand cable and mix the resin. There is the step of rotating the head mechanism in a second direction opposite the first direction to tension the cable bolt in the mine roof.

The present invention is a mine roof bolt for use in a bore hole of a mine with resin. The bolt comprises a strand cable. The bolt comprises a head mechanism attached to the strand cable. The head mechanism includes a hollow fixture made from hot rolled all thread bar threaded on the outside through which the cable extends and to which the cable is attached, and a nut threaded to the fixture.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

In the accompanying drawings, the preferred embodiment of the invention and preferred methods of practicing the invention are illustrated in which:

FIG. 1 is a schematic representation of a mine roof bolt of the present invention.

FIG. 2 is a schematic representation of a bottom end of a mine roof bolt of the present invention.

FIG. 3 is a schematic representation of an invention tool with a mine roof bolt of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals refer to similar or identical parts throughout the several views, and more specifically to FIGS. 1-3 thereof, there is shown a mine roof bolt for use with resin. The bolt comprises a strand cable. The bolt comprises a head mechanism attached to the strand cable which allows the strand cable to be turned in a first direction for mixing the resin and in a second direction opposite the first direction for tensioning the strand cable in the mine roof.

Preferably, the head mechanism includes a hollow fixture 4 threaded on the outside through which the cable extends and to which the cable is attached. The fixture is preferably made from hot rolled all thread bar, described in ASTM A615, incorporated by reference herein. The head mechanism preferably includes a nut 5 threaded to the fixture 4. Preferably, the fixture 4 has a bottom portion which is beveled internally.

The head mechanism preferably includes wedges 7 which are disposed in the beveled portion to grip the cable. Preferably, the fixture 4 has an upper end 15 which is swagged to the cable, although it does not have to be swagged. The head mechanism preferably includes a stop mechanism disposed between the end of the fixture 4 and the wedges 7 to prevent the nut 5 from coming off as the fixture 4 is spun backwards opposite of its threads to cause the cable to mix the resin.

The present invention pertains to a mine roof bolt for use with resin. The bolt comprises a strand cable. The bolt comprises means for allowing the strand cable to be turned in a first direction for mixing the resin and in a second direction opposite the first direction for tensioning the strand cable in the mine roof.

The allowing means is shown in FIGS. 1-3.

The present invention pertains to a method for placing a mine roof bolt in a mine roof. The method comprises the steps of placing a resin cartridge 3 in a bore hole in the mine roof. There is the step of inserting the strand cable of the bolt into the borehole so it pierces the cartridge. There is the step of rotating a head mechanism of the bolt attached to the strand cable in a first direction to rotate the strand cable and mix the resin. There is the step of rotating the head mechanism in a second direction opposite the first direction to tension the cable bolt in the mine roof.

Preferably, there is the step of spinning the fixture 4 of the head mechanism in a direction opposite of threads on the fixture 4. The spinning step preferably includes the step of preventing a nut 5 of the head mechanism from coming off with a stop mechanism of the head mechanism. Preferably, the rotating in a second direction step includes the step of turning the nut 5 in the second direction after the resin has set to tension the bolt.

The present invention includes a method to install a cable bolt with tension. It also has specific hardware (a stop washer 6) and the manner in which it is placed.

The method preferably is to mix in one direction and tension in the opposite direction using a cable bolt.

The present invention is a mine roof bolt for use in a bore hole of a mine with resin. The bolt comprises a strand cable. The bolt comprises a head mechanism attached to the strand cable. The head mechanism includes a hollow fixture made from hot rolled all thread bar threaded on the outside through which the cable extends and to which the cable is attached, and a nut threaded to the fixture.

Preferably, the fixture has a bottom portion which is beveled internally. The head mechanism preferably includes wedges which are disposed in the beveled portion to grip the cable.

The present invention pertains to a method for placing a mine roof bolt in a mine roof. The method comprises the steps of placing a resin cartridge in a bore hole in the mine roof. There is the step of inserting the strand cable of the bolt into the borehole so it pierces the cartridge. There is the step of rotating a head mechanism of the bolt attached to the strand cable in a first direction to rotate the strand cable and mix the resin. There is the step of stopping the rotation of the head mechanism. There is the step of rotating the head mechanism in the first direction to tension the cable bolt in the mine roof. Preferably, the stopping step lasts long enough for the mixed resin to set.

In the operation of the preferred embodiment, the bolt has a stop washer 6 that prevents the nut 5 from coming off during mixing. This washer 6 is held in place by the action of the wedges 7 seating inside the end of the fixture 4. The washer I.D. is the same or slightly larger than the diameter of the entrance to the fixture 4. Since the wedges 7 are tapered and become larger than the entrance diameter and washer I.D., this interference fit holds the washer in place. A roof bolting machine attaches to the insertion tool to spin and tension the bolt, as shown in FIG. 3.

In the prior art, shown on rigid rebar, the stop mechanism is different, either by: 1) damaging the threads at the end; or, 2) by fixing a thin nut on the end of the threads the main nut is prevented from coming off during mixing in the opposite direction.

A multi-strand cable 1 with any of several means of mixing resin 9 in a cartridge 3 attached to the leading end is inserted into a drilled hole 10 in the roof of a mine or tunnel containing the resin. The second or bottom end has a fixture 4 attached to the cable which is threaded on the outside and has a nut 5 threaded to it. A drilled out threaded rebar rod is used as a fixture 4 to hold the cable. These threads 35 on the rebar are manufactured during rolling of the rod in a steel mill versus cut or roll threading a round rod. Examples could be a Dywidag or SAS rod. These threads 35 of a hot rolled all thread bar are better than rolled or cut threads since they do not damage in rough handling in a mine. The threaded fixture 4 is hollow and accepts the strand cable 1. The head mechanism could also be a casting made in a foundry.

The bottom portion of the fixture 4 is beveled internally to accept wedges 7 which grip the swagged mechanically to the cable. A washer 6 (preferably round) is placed as a stop member between the end of the fixture 4 and the wedges 7. The washer can be held by the wedges 7 as an interference fit (between wedges 7 and end of all thread bar-fixture 4), or can be attached to the end of the fixture 4, such as welding to hold it on. The washer provides a flat surface 16 to contact the nut 5 face as a stop means. This may be held in several other means such as welding to the fixture 4. A deep wall socket 13 is used to insert the bolt and spin the resin. The stop washer 6 prevents the nut 5 from coming off as the bolt is spun backwards (opposite of its threads) to mix the resin. After spinning backwards to mix resin, the bolt is held in place until the resin sets, then the nut 5 is turned the other direction to tension the bolt from the nut 5 to the resin anchorage zone.

If it is desired to mix and tighten in the same direction, this can be accomplished for example by using U.S. Pat. No. 5,526,720, incorporated by reference herein, which features a spring loaded wrench to allow both mix spinning and tightening to occur in one direction. When mixing and tightening in the same direction, a stop mechanism does not have to be used.

Although the invention has been described in detail in the foregoing embodiments for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be described by the following claims. 

1. A mine roof bolt for use in a bore hole of a mine with resin comprising: a strand cable; and a head mechanism attached to the strand cable which allows the strand cable to be turned in a first direction for mixing the resin and in a second direction opposite the first direction for tensioning the strand cable in the mine roof.
 2. A bolt as described in claim 1 wherein the head mechanism includes a hollow fixture threaded on the outside through which the cable extends and to which the cable is attached.
 3. A bolt as described in claim 2 wherein the head mechanism includes a nut threaded to the fixture.
 4. A bolt as described in claim 3 wherein the fixture has a bottom portion which is beveled internally.
 5. A bolt as described in claim 4 wherein the head mechanism includes wedges which are disposed in the beveled portion to grip the cable.
 6. A bolt as described in claim 5 wherein the fixture has an upper end which is swaged to the cable.
 7. A bolt as described in claim 6 wherein the head mechanism includes a stop mechanism disposed between the end of the fixture and the wedges to prevent the nut from coming off as the fixture is spun backwards opposite of its threads to cause the cable to mix the resin.
 8. A mine roof bolt for use with resin comprising: a strand cable; and means for allowing the strand cable to be turned in a first direction for mixing the resin and in a second direction opposite the first direction for tensioning the strand cable in the mine roof.
 9. A method for placing a mine roof bolt in a mine roof comprising the steps of: placing a resin cartridge in a bore hole in the mine roof; inserting the strand cable of the bolt into the borehole so it pierces the cartridge; rotating a head mechanism of the bolt attached to the strand cable in a first direction to rotate the strand cable and mix the resin; and rotating the head mechanism in a second direction opposite the first direction to tension the cable bolt in the mine roof.
 10. A method as described in claim 9 including the step of spinning the fixture of the head mechanism in a direction opposite of threads on the fixture.
 11. A method as described in claim 10 wherein the spinning step includes the step of preventing a nut of the head mechanism from coming off with a stop mechanism of the head mechanism.
 12. A method as described in claim 11 wherein the rotating in a second direction step includes the step of turning the nut in the second direction after the resin has set to tension the bolt.
 13. A mine roof bolt for use in a bore hole of a mine with resin comprising: a strand cable; and a head mechanism attached to the strand cable, the head mechanism includes a hollow fixture made from hot rolled all thread bar threaded on the outside through which the cable extends and to which the cable is attached, and a nut threaded to the fixture.
 14. A bolt as described in claim 13 wherein the fixture has a bottom portion which is beveled internally.
 15. A bolt as described in claim 14 wherein the head mechanism includes wedges which are disposed in the beveled portion to grip the cable.
 16. A method for placing a mine roof bolt in a mine roof comprising the steps of: placing a resin cartridge in a bore hole in the mine roof; inserting the strand cable of the bolt into the bore hole so it pierces the cartridge; rotating a head mechanism of the bolt attached to the strand cable in a first direction to rotate the strand cable and mix the resin; stopping the rotation of the head mechanism; and rotating the head mechanism in the first direction to tension the cable bolt in the mine roof. 